Infestation in place with row overlooking river (6)
I believe the answer is:
plague
'infestation' is the definition.
(I know that infestation can be written as plague)
'place with row overlooking river' is the wordplay.
I cannot really understand how this works, but
'place' could be 'pl' (abbreviation used in postal addresses) and 'pl' is found within the answer.
The remaining letters 'ague' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for plague that I've seen before include "fatal outbreak" , "Deadly contagious disease, or a swarm of locusts" , "Widespread, contagious and destructive disease" , "Deadly epidemic" , "Outbreak of a deadly disease, or infestation of pest like locusts" .)