Combined after base came into view (7)
I believe the answer is:
emerged
'came into view' is the definition.
(I've seen this before)
'combined after base' is the wordplay.
I cannot really see how this works, but
'combined' could be 'merged' ('merge' can be a synonym of 'combine') and 'merged' is located in the answer.
'base' could be 'e' (Euler's number - base of natural logarithms) and 'e' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for emerged that I've seen before include "Came into view or became apparent" , "Deem Reg to have come out" , "Came forth" , "Came out, became known" , "Transpired" .)