Challenger emerges from den, getting up about five (5)
I believe the answer is:
rival
'challenger' is the definition.
(I know that challenger can be written as rival)
'den getting up about five' is the wordplay.
'den' becomes 'lair' (synonyms).
'getting up' shows that the letters should be reversed in order.
'about' indicates putting letters inside.
'five' becomes 'V' (Roman numeral).
'lair' in reverse letter order is 'rial'.
'rial' enclosing 'v' is 'RIVAL'.
'emerges from' acts as a link.
(Other definitions for rival that I've seen before include "Compete with" , "Close competitor" , "Contender" , "Someone you hope to defeat" , "Person in direct competition" .)