One of the Stones in Gaga: Telephone (5)
I believe the answer is:
agate
'one of the stones' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'in gaga telephone' is the wordplay.
'in' indicates a hidden word.
'AGATE' can be found hidden inside 'gaga telephone'.
Can you help me to learn more?
(Other definitions for agate that I've seen before include "marble" , "Variegated chalcedony" , "Decorative stone" , "Onyx" , "Variety of chalcedony" .)