Pip covers head of timid horse (5)
I believe the answer is:
steed
'horse' is the definition.
(steed is a kind of horse)
'pip covers head of timid' is the wordplay.
'pip' becomes 'seed' (I've seen this before).
'covers' is an insertion indicator.
'head of' suggests taking the first letters.
The initial letter of 'timid' is 't'.
'seed' going around 't' is 'STEED'.
(Other definitions for steed that I've seen before include "Warhorse" , "Swift horse" , "Powerful horse" , "(Poetic) horse" , "ride" .)