By entering, got my teeth into it twice slowly (3,2,3)
I believe the answer is:
bit by bit
'slowly' is the definition.
(I've seen this in another clue)
'by entering got my teeth into it twice' is the wordplay.
I cannot really understand how this works, but
'by' is present in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'twice' could be 'bi' (eg biannual, biweekly) and 'bi' is found within the answer.
The remaining letters 'bit' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bit by bit that I've seen before include "Two adjacent pieces" , "What might be found in tack room" , "Piecemeal" , "in a gradual sequence" , "Gradually, a little at a time" .)