Father Thomas shows poignancy (6)
I believe the answer is:
pathos
'poignancy' is the definition.
(I've seen this before)
'father thomas' is the wordplay.
I cannot really understand how this works, but
'father' could be 'pa' (pa can mean dad or father) and 'pa' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'shows' is the link.
Can you help me to learn more?
(Other definitions for pathos that I've seen before include "A quality that arouses pity or sorrow" , "Hot spa (anag) - sadness" , "The quality moves one to pity" , "Pitifulness" , "Quality of attracting pity" .)