For the little creature carrying it, it’s a strain (6)
I believe the answer is:
effort
'it's a strain' is the definition.
(I've seen this before)
'for the little creature carrying' is the wordplay.
'the little creature' becomes 'eft' (I've seen this before).
'carrying' means one lot of letters goes inside another.
'for' going inside 'eft' is 'EFFORT'.
'it' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for effort that I've seen before include "Toil" , "Hard mental or physical work" , "For eft (anag.)" , "Try - labour - pains" , "Attempt, energy exerted" .)