Monk's garb is hot to some extent (5)
I believe the answer is:
habit
'monk's garb' is the definition.
(I've seen this in another clue)
'hot to some extent' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'to some extent' becomes 'a bit' (to a small extent).
'h'+'abit'='HABIT'
'is' is the link.
(Other definitions for habit that I've seen before include "What might one have a regular tendency to" , "Regular practice" , "Settled practice" , "Monk's robe or repetitive action" , "Custom or monk's robe" .)