Simple dwelling, on reflection, hard to flog (5)
I believe the answer is:
birch
'flog' is the definition.
(birching is a kind of flogging)
'simple dwelling on reflection hard' is the wordplay.
'simple dwelling' becomes 'crib' (I have seen 'urban dwelling' mean 'crib' so perhaps 'dwelling' could also mean 'crib'. I am not sure about the 'simple' bit.).
'on reflection' says the letters should be written backwards.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'crib' backwards is 'birc'.
'birc'+'h'='BIRCH'
'to' is the link.
Can you help me to learn more?
(Other definitions for birch that I've seen before include "Flogging rod" , "to beat the rest?" , "'Slender tree, the bark could be silver (5)'" , "Tree, beat" , "Hardy tree" .)