Senseless way in which space and time end (5)
I believe the answer is:
inane
'senseless way in which' is the definition.
'inane' can be an answer for 'senseless' (I've seen this before). I am not sure about the remainder of the definition.
'space and time end' is the wordplay.
'space' becomes 'ina' (I can't explain this - if you can you should believe this answer much more).
'and' becomes 'n' (common abbreviation for 'and').
'end' indicates one should take the final letters.
The last letter of 'time' is 'e'.
'ina'+'n'+'e'='INANE'
Can you help me to learn more?
(Other definitions for inane that I've seen before include "Thick" , "Foolish, fatuous" , "Silly or senseless" , "Witless and pointless" , "Fatuous, vacuous" .)