Provides commentary for girl leading seaman round gallery (9)
I believe the answer is:
annotates
'provides commentary' is the definition.
(to annotate is to provide written commentary)
'girl leading seaman round gallery' is the wordplay.
'girl' becomes 'anno' (I can't explain this - if you can you should believe this answer much more).
'leading' says to take the initial letters.
'round' is an insertion indicator.
'gallery' becomes 'tate' (Tate Modern, Tate Britain etc).
The initial letter of 'seaman' is 's'.
'anno'+'s'='annos'
'annos' going around 'tate' is 'ANNOTATES'.
'for' is the link.
(Another definition for annotates that I've seen is " Adds comments to (a document)".)