Pastry enthusiast welcoming learner (4)
I believe the answer is:
flan
'pastry' is the definition.
(I know that flan is a type of pie)
'enthusiast welcoming learner' is the wordplay.
'enthusiast' becomes 'fan' (fan is a kind of enthusiast).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'fan' placed around 'l' is 'FLAN'.
(Other definitions for flan that I've seen before include "Quiche-like dish" , "Open pastry dessert" , "Quiche" , "Open-topped tart" , "Open pastry or sponge case with tasty filling" .)