Astrologers seen in shorter spells? (4)
I believe the answer is:
magi
'astrologers' is the definition.
'shorter spells?' is the wordplay.
'shorter' means to remove the last letter.
'spells?' becomes 'magic' (I've seen this before).
'magic' with its final letter taken off is 'MAGI'.
'seen in' acts as a link.
(Other definitions for magi that I've seen before include "Caspar, Melchior and Balthazar" , "Biblical wise men" , "Nativity story wise men" , "Three Wise Men of the Bible" , "Bearers of gold, frankincense and myrrh?" .)