Packed theatre rented middle of field (7)
I believe the answer is:
replete
'packed' is the definition.
(thesaurus)
'theatre rented middle of field' is the wordplay.
'theatre' becomes 'rep' (I've seen this in other clues).
'rented' becomes 'let' (I've seen this before).
'middle of' means to look at the middle letters.
The middle letter of 'field' is 'e'.
'rep'+'let'+'e'='REPLETE'
(Other definitions for replete that I've seen before include "Filled to satiety" , "Sated by food" , "Well-fed" , "Filled to satisfaction" , "Chock-a-block" .)