Rock band (7)

I believe the answer is:

stratum

'rock band' is the definition.
(I've seen this before)

This is all the clue.

(Other definitions for stratum that I've seen before include "Layer (of rock)" , "Bed of sedimentary rock" , "(Geological) layer" , "rock band" , "Social class - level" .)

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app