Jumper for woolly garment, initially (4)
I believe the answer is:
frog
'jumper' is the definition.
(something which jumps)
'woolly garment initially' is the wordplay.
'woolly' becomes 'fro' (I can't explain this - if you can you should give a lot more credence to this answer).
'initially' suggests taking the first letters.
The first letter of 'garment' is 'g'.
'fro'+'g'='FROG'
'for' is the link.
Can you help me to learn more?
(Other definitions for frog that I've seen before include "Small creature" , "Croaking amphibian" , "Batrachian" , "Tailless hopper" , "An amphibian; a track plate" .)