In certain ways there's a need to relax (7)
I believe the answer is:
slacken
'relax' is the definition.
(I know that relax can be written as slacken)
'in certain ways there's a need' is the wordplay.
'in' is an insertion indicator.
'certain ways' becomes 'sen' (I can't justify this - if you can you should give a lot more credence to this answer).
'there's a need' becomes 'lack' (to lack something is to be in need of it).
'sen' placed around 'lack' is 'SLACKEN'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for slacken that I've seen before include "reduce tension" , "Loosen -- become less busy" , "Loosen, eg, a rope" , "Make looser" , "relax" .)