Rob Gell uncovered foreign coin (6)
I believe the answer is:
nickel
'foreign coin' is the definition.
'nickel' can be an answer for 'coin' (nickel is a kind of coin). I'm not certain of the 'foreign' bit.
'rob gell uncovered' is the wordplay.
'rob' becomes 'nick' (I can't justify this - if you can you should believe this answer much more).
'uncovered' means to look at the middle letters.
The middle of 'gell' is 'el'.
'nick'+'el'='NICKEL'
Can you help me to learn more?
(Other definitions for nickel that I've seen before include "Metal - US coin" , "Silvery white metal" , "American five cent piece" , "Metal; five US cents" , "One twentieth of a US dollar" .)