To clean inside of shoe, sit in a seat, on reflection (8)
I believe the answer is:
sanitise
'to clean' is the definition.
(I know that sanitise is a more specific form of the action clean)
'of shoe sit in a seat on reflection' is the wordplay.
'of' indicates the answer is hidden within the clue.
'on reflection' is a reversal indicator.
'esitinas' is hidden within 'shoe sit in a seat'.
'esitinas' written backwards gives 'SANITISE'.
'inside' is the link.
(Other definitions for sanitise that I've seen before include "Make hygienic or more acceptable" , "Clean up, make hygienic like a Sistine" , "disinfect" , "Make hygienic, sterilise" , "Make hygienic being in siesta" .)