Tank put right in the nicest possible way (7)
I believe the answer is:
cistern
'tank' is the definition.
(I know that cistern is a type of tank)
'right in the nicest possible way' is the wordplay.
I cannot really see how this works, but
'right' could be 'r' (abbreviation) and 'r' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'way' could be 's' (Compass direction - South) and 's' is present in the answer.
This explanation may well be incorrect...
'put' acts as a link.
Can you help me to learn more?
(Other definitions for cistern that I've seen before include "WC water tank" , "bit of toilet" , "Toilet water reservoir" , "Tank, reservoir" , "Water storage tank" .)