Go in hope, positively (3)
I believe the answer is:
pep
'go' is the definition.
(both can mean energy or vitality)
'in hope positively' is the wordplay.
'in' says the answer is hidden in the clue.
'PEP' can be found hidden inside 'hope positively'.
(Other definitions for pep that I've seen before include "Go" , "Palindromic energy or vim" , "Energy or enthusiasm" , "Get-up-and-go" , "Palindromic vim and vigour" .)