In poor health, putting to sea without strength at first (6)
I believe the answer is:
ailing
'in poor health' is the definition.
(an ailing person is unwell)
'to sea without strength at first' is the wordplay.
I cannot really see how this works, but
'at' could be 'in' (synonymous in some cases - eg at school, in school) and 'in' is found within the answer.
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is found within the answer.
The remaining letters 'alg' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'putting' acts as a link.
Can you help me to learn more?
(Other definitions for ailing that I've seen before include "feeling sick" , "Sickly, poorly" , "Infertile" , "Troubled in mind or body" , "In poor health" .)