Concert -- almost remember about it (7)
I believe the answer is:
recital
'concert' is the definition.
(I've seen this before)
'almost remember about it' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'remember' becomes 'recall' (synonyms).
'about' means one lot of letters goes inside another.
'recall' with its last letter taken off is 'recal'.
'recal' placed around 'it' is 'RECITAL'.
(Other definitions for recital that I've seen before include "Article (anag)" , "Performance of music by soloist" , "Maybe solo musical performance" , "Performance, usually musical" , "Concert performed by a solo musician" .)