Fear being overwhelmed by germ in algae (7)
I believe the answer is:
seaweed
'algae' is the definition.
(seaweed is a kind of algae)
'fear being overwhelmed by germ' is the wordplay.
'fear' becomes 'awe' (awe is a kind of fear).
'being overwhelmed by' is an insertion indicator (inserted letters get absorbed or overwhelmed).
'germ' becomes 'seed' (synonyms).
'awe' inserted within 'seed' is 'SEAWEED'.
'in' is the link.
(Other definitions for seaweed that I've seen before include "Marine growth" , "Laver perhaps" , "Main plant" , "Plant such as kelp" , "What may be cast up on shore" .)