Underwear hamster chewed up, including first of lingerie (8)
I believe the answer is:
thermals
'underwear' is the definition.
(I know that thermals is a type of underwear)
'hamster chewed up including first of lingerie' is the wordplay.
'chewed up' indicates an anagram.
'including' is an insertion indicator.
'first of lingerie' becomes 'l' (1st letter of 'lingerie').
'hamster' is an anagram of 'thermas'.
'thermas' going around 'l' is 'THERMALS'.
(Other definitions for thermals that I've seen before include "Rising currents of hot air" , "Warm underwear" , "Upward air currents - winter warmers" , "Long johns" , "Warm clothes" .)