Fast learner overwhelms Wimbledon’s second seed (6)
I believe the answer is:
lentil
'seed' is the definition.
(I've seen this before)
'fast learner overwhelms wimbledon's second' is the wordplay.
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'overwhelms' means one lot of letters goes inside another.
'wimbledon's second' becomes 'i' (2nd letter of 'wimbledon').
'lent'+'l'='lentl'
'lentl' going around 'i' is 'LENTIL'.
(Other definitions for lentil that I've seen before include "Pulse used in cooking" , "High-protein pulse" , "Pulse used in soup" , "Leguminous vegetable" , "Small seed used for food" .)