Horse of Wimbledon favourite has temperature (5)
I believe the answer is:
steed
'horse' is the definition.
(steed is a kind of horse)
'wimbledon favourite has temperature' is the wordplay.
'wimbledon favourite' becomes 'seed' (tennis players are seeded).
'has' means one lot of letters goes inside another.
'temperature' becomes 't' (abbreviation).
'seed' placed around 't' is 'STEED'.
'of' acts as a link.
(Other definitions for steed that I've seen before include "Warhorse" , "Literary term for horse" , "ride" , "Spirited horse" , "A mount (poet.)" .)