Digress and explode at a Northern man admitting volunteers (2,3,2,1,7)

'digress' is the definition.
I know nothing about this answer so I can't tell whether this works.

'and explode at a northern man admitting volunteers' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'explode' could be 'gooff' (going off is a kind of exploding) and 'gooff' is found within the answer.
'at' is within the answer.
'a' is found in the answer.
'northern' could be 'n' (abbreviation e.g. N. Ireland) and 'n' is found in the answer.
'volunteers' could be 'ta' (abbreviation for Territorial Army) and 'ta' is found in the answer.
The remaining letters 'get' 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?