Gasped out loud: maybe dog's set about duck (8)
I believe the answer is:
sidestep
'duck' is the definition.
(both can mean to avoid)
'gasped out loud maybe dog's set about' is the wordplay.
'gasped' becomes 'sighed'.
'out loud' indicates a 'sounds like' (homophone) clue.
'maybe dog's' becomes 'pet's' (dogs are often kept as pets).
'set about' says the letters should be written backwards.
'sighed' sounds like 'side'.
'pets' back-to-front is 'step'.
'side'+'step'='SIDESTEP'
(Other definitions for sidestep that I've seen before include "Dodge - circumvent" , "To avoid" , "Find a way round" , "Dodge (an issue?)" , "Shift to right or left" .)