Hit up half a century frequently (4)
I believe the answer is:
loft
'hit up' is the definition.
(I've seen this in another clue)
'half a century frequently' is the wordplay.
I cannot really understand how this works, but
'frequently' could be 'oft' (oft can mean frequently, eg oft-quoted) and 'oft' is found within the answer.
A single letter 'l' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for loft that I've seen before include "Elevation" , "Uppermost room" , "Backward slope in face of golf club" , "Send ball in a high arc - in a barn?" , "Place for keeping racing pigeons" .)