Cold? Warmth in small bulb (5)
I believe the answer is:
clove
'small bulb' is the definition.
(I've seen this before)
'cold? warmth' is the wordplay.
'cold?' becomes 'c' (eg on taps).
'warmth' becomes 'love' (I can't justify this - if you can you should believe this answer much more).
'c'+'love'='CLOVE'
'in' is the link.
Can you help me to learn more?
(Other definitions for clove that I've seen before include "Pungent spice" , "Flower bud used as a spice" , "Aromatic bud" , "Spice, used whole or ground" , "Spicy bud - section of garlic" .)