Organisational reason to take one's temperature (8)
I believe the answer is:
logistic
'organisational' is the definition.
(logistics means organising things)
'reason to take one's temperature' is the wordplay.
'reason' becomes 'logic' (logic is using reason).
'to take' means one lot of letters goes inside another (inserted letters are taken in).
'one's' becomes 'I's' (Roman numeral).
'temperature' becomes 't' (abbreviation).
'is'+'t'='ist'
'logic' placed around 'ist' is 'LOGISTIC'.
(Other definitions for logistic that I've seen before include "of detailed planning" , "Relating to military support and movements" .)