Wearing PE kit, lower leg's very cold (9)
I believe the answer is:
perishing
'very cold' is the definition.
(perishing can mean extremely cold)
'wearing pe kit lower leg's' is the wordplay.
'wearing' means one lot of letters goes inside another.
'kit' becomes 'rig' (I've seen this in other clues).
'lower leg' becomes 'shin' (I've seen this in another clue).
'pe'+'rig'='perig'
'perig' enclosing 'shin' is 'PERISHING'.
(Other definitions for perishing that I've seen before include "Dying" , "going west" .)