Foundation dismissing current singer (4)
I believe the answer is:
bass
'singer' is the definition.
(bass is a kind of singer)
'foundation dismissing current' is the wordplay.
'foundation' becomes 'basis' (synonyms).
'dismissing' suggests deleting specific letters.
'current' becomes 'i' (symbol for electric current).
'basis' with 'i' taken away is 'BASS'.
(Other definitions for bass that I've seen before include "Big percussion instrument" , "Booming percussion instrument" , "Deep-toned" , "Lowest male singer" , "Very low - perch" .)