Puffs along to church wearing boots (5)

'wearing boots' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot understand how they can define each other.

'puffs along to church' is the wordplay.
'puffs along' becomes 'ugs' (I can't justify this - if you can you should give a lot more credence to this answer).
'to' says to put letters next to each other (I've seen this in other clues).
'church' becomes 'ch' (common abbreviation).
'ugs' put after 'ch' is 'CHUGS'.

Can you help me to learn more?