Old writer in front of gallery for launch (7)
I believe the answer is:
opening
'launch' is the definition.
(I've seen this before)
'old writer in front of gallery' is the wordplay.
'old' becomes 'o' (abbreviation).
'writer' becomes 'pen' (something which writes).
'front of' indicates taking the first letters (the letter at the front of the word).
The initial letter of 'gallery' is 'g'.
'o'+'pen'+'in'+'g'='OPENING'
'for' is the link.
(Other definitions for opening that I've seen before include "First -- beginning" , "Opportunity; gap" , "Inauguration" , "Yawning" , "(Official) start - gap" .)