There's a surplus circuit in the passage (7)
I believe the answer is:
extract
'passage' is the definition.
(I know that extract is a type of passage)
'there's a surplus circuit in the' is the wordplay.
'there's a surplus' becomes 'extra' (I've seen this before).
'circuit in' becomes 'c' (I can't justify this - if you can you should give a lot more credence to this answer).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'extra'+'c'+'t'='EXTRACT'
Can you help me to learn more?
(Other definitions for extract that I've seen before include "concentrate" , "Pull out as with tooth (7)" , "Separate, in a mining sense" , "Clipping" , "Uproot by force" .)