Hot air! Fix sharp bend? (7)
I believe the answer is:
hairpin
'sharp bend?' is the definition.
(I've seen this before)
'hot air fix' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'fix' becomes 'pin' (to pin is to fix in place).
'h'+'air'+'pin'='HAIRPIN'
(Other definitions for hairpin that I've seen before include "Fastener for tresses" , "Road formation" , "stuck in a lock?" , "grip?" , "Nasty road bend or aid to coiffure" .)