ਸਭ ਤੇ ਵਡਾ ਸਤਿਗੁਰੁ ਨਾਨਕੁ ਜਿਨਿ ਕਲ ਰਾਖੀ ਮੇਰੀ॥
The meaning of this pankiti is that Satgur Nanak is the greatest of all, who has kept my honour. Some teekakaars have interpreted ਕਲ as Shakti or power. Then the meaning would be that Satgur Nanak is the greatest of all who maintained my shakti or kept my shakti.
Here are more pankitis that refer specially to Siri Guru Nanak Dev jee:
ਸਭੇ ਕਾਜ ਸੁਹੇਲੜੇ ਥੀਏ ਗੁਰੁ ਨਾਨਕੁ ਸਤਿਗੁਰੁ ਤੁਠਾ ॥1॥
(All my works or tasks were done easily when Guru Nanak became merciful/kind/benevolent)
ਗੁਰੁ ਨਾਨਕੁ ਤੁਠਾ ਮਿਲਿਆ ਹਰਿ ਰਾਇ ॥
(When Guru Nanak became merciful, I met Vaheguru).
ਸਭੇ ਇਛਾ ਪੂਰੀਆ ਜਾ ਪਾਇਆ ਅਗਮ ਅਪਾਰਾ ॥
ਗੁਰੁ ਨਾਨਕੁ ਮਿਲਿਆ ਪਾਰਬ੍ਰਹਮੁ ਤੇਰਿਆ ਚਰਣਾ ਕਉ ਬਲਿਹਾਰਾ ॥੪॥੧॥੪੭॥
Notice that the above pankiti has aunkad on both ਗੁਰੁ ਨਾਨਕੁ and for this reason this is referring to Siri Guru Nanak Dev jee. The shabad is of Siri Guru Arjun Dev jee.
In this pankiti, the word ਮਿਲਿਆ is a Dehli Deepak. What Dehli-Deepak means is such lamp (Deepak) that is placed right on the door (dehli). This way the lamp gives light on both sides of the door. Same way a word (averb, an adjective etc) that is connected to two words is called a Dehli Deepak. In this case, this word ਮਿਲਿਆ is connected to both ਗੁਰੁ ਨਾਨਕੁ and ਪਾਰਬ੍ਰਹਮੁ . The meaning would be clear if I write it in Punjabi as follows:
ਗੁਰੁ ਨਾਨਕੁ ਮਿਲਿਆ, (ਤਾਂ ਮਿਲਿਆ) ਪਾਰਬ੍ਰਹਮੁ...
And on who's charan is Guru Sahib going sacrifice? It has to be the Charan of ਗੁਰੁ ਨਾਨਕੁ because he enabled them to meet ਪਾਰਬ੍ਰਹਮੁ.
Based on the discussion above, the meaning of this pankiti is: When I met Guru Nanak, then I met Vaheguru; I am sacrifice on Siri Guru Nanak Dev jee (who enabled me to meet Vaheguru).
There are numerous such pankitis, mostly by Siri Guru Arjun Dev jee, that talk about Siri Guru Nanak Dev jee and how through his mercy alone, one can meet Vaheguru.
Most of the times the word "Nanak" is without aunkad or sihaari and in such situations, it is used as a poetic name. Many times it also means "O Nanak". Guru Sahib addresses himself while ending a shabad. At times, it also means "Nanak ne" but most of the times the meaning of "Nanak ne" is derived from ਨਾਨਕਿ as is the case in the following pankitis:
ਜਨ ਨਾਨਕਿ ਬ੍ਰਹਮੁ ਪਛਾਣਿਆ ਹਰਿ ਕੀਰਤਿ ਕਰਮ ਕਮਾਉ ॥2॥
(Servant Nanak has realised Brahm (Vaheguru) by doing the Karma of singing praises)
ਹਰਿ ਕੈ ਦਰਿ ਵਰਤਿਆ ਸੁ ਨਾਨਕਿ ਆਖਿ ਸੁਣਾਇਆ ॥
(What ever occurred at the door of Vaheguru, that Nanak (Guru Nanak) has narrated).
Bhul chuk dee maafi jee.