In flipping work, one has very thick skin (5)
I believe the answer is:
hippo
'one has very thick skin' is the definition.
I can't tell whether this definition defines the answer.
'in flipping work' is the wordplay.
'in' becomes 'hip' (both can mean fashionable).
'flipping' shows that the letters should be reversed in order.
'work' becomes 'op' (abbreviation for opus).
'op' back-to-front is 'po'.
'hip'+'po'='HIPPO'
Can you help me to learn more?
(Other definitions for hippo that I've seen before include "Augustine's place" , "African animal (shortened)" , "Semiaquatic animal" , "Aquatic pachyderm" , "One wallows in mud" .)