Does all one can to get rid of undesirable elements (7)
I believe the answer is:
strains
'does' is the definition.
The definition and answer can be both related to bodily activities as well as being verbs in their -s form.
Perhaps you can see an association between them that I can't see?
'all one can to get rid of undesirable elements' is the wordplay.
I cannot really understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'elements' could be 'ns' (N is an example) and 'ns' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for strains that I've seen before include "Tries very hard" , "Melodies" , "Stresses and - -" .)