Set about catching wild dog that's hard going to put away (6)
I believe the answer is:
stodge
'that's hard going to put away' is the definition.
(as in stodgy food)
'set about catching wild dog' is the wordplay.
'about' indicates an anagram.
'catching' is an insertion indicator.
'wild' indicates anagramming the letters.
'set' is an anagram of 'ste'.
'dog' anagrammed gives 'odg'.
'ste' placed around 'odg' is 'STODGE'.
(Other definitions for stodge that I've seen before include "Indigestible or dull food" , "Heavy solid food" , "Heavy, often starchy, food" , "Heavy pud" , "Heavy stuff" .)