Relevant to a microbe on an antelope's back (7)
I believe the answer is:
germane
'relevant' is the definition.
(similar in meaning)
'a microbe on an antelope's back' is the wordplay.
'a microbe' becomes 'germ' ('germ' can be a synonym of 'microbe').
'on' means one lot of letters go next to another.
'back' indicates one should take the final letters.
The final letter of 'antelope' is 'e'.
'germ'+'an'+'e'='GERMANE'
'to' is the link.
(Other definitions for germane that I've seen before include "Apposite" , "Relevant, to the point" , "apt" , "Material" , "Relative or appropriate" .)