Assess the condition I'm in (8)
I believe the answer is:
estimate
'assess' is the definition.
(I know that assess is a more specific form of the action estimate)
'condition i'm in' is the wordplay.
'condition' becomes 'estate' (I've seen this before).
'in' means one lot of letters goes inside another.
'estate' going around 'im' is 'ESTIMATE'.
'the' acts as a link.
(Other definitions for estimate that I've seen before include "Statement giving the likely cost of a job" , "Tease Tim (anag.)" , "Calculate approximately" , "Calculate in approximate way" , "Judge the worth of" .)