Feature of Arctic upsetting Father Cecil endlessly (6)
I believe the answer is:
icecap
'feature of arctic' is the definition.
'icecap' can be an answer for 'feature' (I have seen 'Polar feature ' mean 'icecap' so perhaps 'feature' could also mean 'icecap'). I'm not sure about the 'of arctic' bit.
'upsetting father cecil endlessly' is the wordplay.
'upsetting' is a reversal indicator.
'father' becomes 'pa' (pa can mean dad or father).
'endlessly' means to remove the last letter.
'pa'+'cecil'='pacecil'
'pacecil' with its last letter taken away is 'paceci'.
'paceci' in reverse letter order is 'ICECAP'.
Can you help me to learn more?
(Other definitions for icecap that I've seen before include "frozen summit" , "mass covering the top of Everest?" , "Permanently frozen covering of land" , "Frozen topping" , "hard water area" .)