Man seemingly going to great lengths for poet (10)
I believe the answer is:
longfellow
'poet' is the definition.
(Henry Wadsworth Longfellow, 1807-1882)
'man seemingly going to great lengths' is the wordplay.
I cannot quite see how this works, but
'man' could be 'fellow' (fellow is a kind of man) and 'fellow' is located in the answer.
'going' could be 'on' (both can mean functioning or activated) and 'on' is present in the answer.
'great' could be 'g' (abbreviation in place names) and 'g' is located in the answer.
A single letter 'l' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'for' acts as a link.
Can you help me to learn more?
(Other definitions for longfellow that I've seen before include "American poet, author of 17" , "Song of_Hiawatha poet" , "Hiawatha poet" .)