Bonus for us, getting tailored old clothes (4,5)
I believe the answer is:
plus fours
'old clothes' is the definition.
(old-fashioned type of trousers)
'bonus for us getting tailored' is the wordplay.
'bonus' becomes 'plus' (I've seen this before).
'getting' means one lot of letters go next to another.
'tailored' indicates an anagram (the letters are customised ).
'for'+'us'='forus'
'forus' anagrammed gives 'fours'.
'plus'+'fours'='PLUS-FOURS'
(Other definitions for plus fours that I've seen before include "Sportswear" , "Bags" , "Old golfwear" , "Surplus of golf knickerbockers" , "golfer's wear" .)