Sit with me and go silly in self-love (7)
I believe the answer is:
egotism
'self-love' is the definition.
(I've seen this before)
'sit with me and go silly' is the wordplay.
'with' says to put letters next to each other.
'and' means one lot of letters go next to another.
'silly' is an anagram indicator.
'me' after 'go' is 'gome'.
'sit' after 'gome' is 'gomesit'.
'gomesit' anagrammed gives 'EGOTISM'.
'in' acts as a link.
(Other definitions for egotism that I've seen before include "Self-love" , "Excessive conceit" , "Self-obsession" , "Obsession with oneself" , "Self-importance" .)