Sweat breaking out? Rubbish (5)
I believe the answer is:
waste
'rubbish' is the definition.
(I know that rubbish can be written as waste)
'sweat breaking out?' is the wordplay.
'breaking out?' indicates an anagram.
'sweat' with letters rearranged gives 'WASTE'.
(Other definitions for waste that I've seen before include "''.... not, want not''" , "Refuse, garbage, rubbish" , "Become gradually weaker" , "Use inefficiently or inappropriately" , "Uncultivated area" .)