Unearth little dog I had briefly rejected (3,2)
I believe the answer is:
dig up
'unearth' is the definition.
(I've seen this in another clue)
'little dog i had briefly rejected' is the wordplay.
'little dog' becomes 'pug' (I've seen this in another clue).
'i had briefly' becomes 'id' ('I'd' is a contraction of 'I had').
'rejected' says the letters should be written backwards.
'pug'+'id'='pugid'
'pugid' in reverse letter order is 'DIG UP'.
(Other definitions for dig up that I've seen before include "Find" , "Exhume" , "Unearth" , "Disinter" , "Uncover (something hidden)" .)