Try to pot one red, initially maintaining break, finally switching to the rest (4,1,8)
I believe the answer is:
take a breather
'rest' is the definition.
(synonyms)
'try to pot one red initially maintaining break finally switching to' is the wordplay.
I cannot really see how this works, but
'one' could be 'the' (both can introduce a definite example of something) and 'the' is found within the answer.
'red' could be 'r' (I've seen this in other clues) and 'r' is found within the answer.
'break' could be 'takea' (synonyms) and 'takea' is located in the answer.
The remaining letters 'bear' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'the' acts as a link.
Can you help me to learn more?
(Another definition for take a breather that I've seen is " Stop for a short rest".)