Touchingly, showed undue greed for a portion of fish! (8)
I believe the answer is:
fingered
'touchingly showed' is the definition.
'fingered' can be an answer for 'showed' (fingering is a kind of showing). I am not certain of the 'touchingly' bit.
'undue greed for a portion of fish' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'greed' is 'gered' which is located in the answer.
'portion of fish' could be 'fin' (fish have fins) and 'fin' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for fingered that I've seen before include "with digital equipment" , "Did some shopping" , "Identified as guilty" .)