You hope they won't be the thorns in your side! (4,5)

'you hope they won't be the thorns in your' is the definition.
The definition suggests an adverb but the answer is not.

'side' is the wordplay.
I cannot really understand how this works, but
'side' could be 'team' (a side is a sporting team) and 'team' is present in the answer.
The remaining letters 'mates' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...