Jewel gleams oddly (3)
I believe the answer is:
gem
'jewel' is the definition.
(I know that jewel can be written as gem)
'gleams oddly' is the wordplay.
'oddly' indicates alternate letters (letters in odd-numbered positions).
The alternating letters of 'gleams' are 'GEM'.
(Other definitions for gem that I've seen before include "Setter might bed this" , "Valuable stone" , "Half of 7 [SIGN OF THE ZODIAC]" , "36 Across or any other jewel" , "A jewel or precious stone" .)