Begins as hooker in depleted scrums (6)
I believe the answer is:
starts
'begins' is the definition.
('start' can be a synonym of 'begin')
'hooker in depleted scrums' is the wordplay.
'hooker' becomes 'tart' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' is an insertion indicator.
'depleted' says to hollow out the word (remove centre letters).
'scrums' with its centre removed is 'ss'.
'tart' going within 'ss' is 'STARTS'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for starts that I've seen before include "origins?" , "Begins - or jumps as with fright" , "Begins or makes sudden movement as from surprise" , "jerks" , "Makes sudden movement from pain or surprise" .)