Rents structure for firm (5)
I believe the answer is:
stern
'firm' is the definition.
(thesaurus)
'rents structure' is the wordplay.
'structure' indicates an anagram.
'rents' anagrammed gives 'STERN'.
'for' acts as a link.
(Other definitions for stern that I've seen before include "Demanding < back" , "Inflexible; back" , "Ship's rear" , "discipline" , "Strict, austere" .)