Second group hit hotel room to get sweaty (5,4)

'second group' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?

'hit hotel room to get sweaty' is the wordplay.
I cannot really understand how this works, but
'hit' could be 'bat' (batting is a kind of hitting) and 'bat' is present in the answer.
'hotel' could be 'h' (phonetic alphabet) and 'h' is found in the answer.
'room' could be 'steam' (steam room is a kind of room) and 'steam' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?