Admiral's first to board ocean rib to perform exercises like these (9)
I believe the answer is:
anaerobic
'exercises like these' is the definition.
The definition suggests an adverb but the answer is not.
'admiral's first to board ocean rib to perform' is the wordplay.
'admiral's first' becomes 'a' (1st letter of 'admiral').
'to board' means one lot of letters goes inside another (inserted letters come on board).
'to perform' is an anagram indicator (I've seen 'performed' mean this).
'ocean'+'rib'='oceanrib'
'oceanrib' is an anagram of 'anerobic'.
'a' inserted within 'anerobic' is 'ANAEROBIC'.
Can you help me to learn more?
(Other definitions for anaerobic that I've seen before include "functional without O2" , "lacking in inspiration?" .)