Cover of Escort: a celebrity back issue (7)
I believe the answer is:
emanate
'issue' is the definition.
(both can mean to give out or radiate)
'cover of escort a celebrity back' is the wordplay.
'cover of' says to hollow out the word (remove centre letters) (only the letters which cover the word).
'celebrity' becomes 'name' (as in a 'big name').
'back' is a reversal indicator.
'escort' with its centre taken out is 'et'.
'et'+'a'+'name'='etaname'
'etaname' in reverse letter order is 'EMANATE'.
(Other definitions for emanate that I've seen before include "Issue forth, from a source" , "Proceed or issue forth" , "Come out (of source)" , "Give out, emit" , "Send out" .)