Less bothered about increase in seats (7)
I believe the answer is:
saddles
'seats' is the definition.
(saddle is a kind of seat)
'less bothered about increase' is the wordplay.
'bothered' indicates an anagram.
'about' is an insertion indicator.
'increase' becomes 'add' (I've seen this before).
'less' with letters rearranged gives 'sles'.
'sles' enclosing 'add' is 'SADDLES'.
'in' acts as a link.
(Other definitions for saddles that I've seen before include "Bicycle seats" , "Riders' seats" , "Jockeys' seats" , "These joints of meat" , "Burdens" .)