Court order investigations finally into all blood groups? (4)
I believe the answer is:
asbo
'court order' is the definition.
(I've seen this before)
'investigations finally into all blood groups?' is the wordplay.
'finally' suggests the final letters.
'into' indicates putting letters inside.
'all blood groups?' becomes 'abo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The final letter of 'investigations' is 's'.
's' going inside 'abo' is 'ASBO'.
Can you help me to learn more?
(Other definitions for asbo that I've seen before include "Order made for bad behaviour" , "Reprimand for anti-social behaviour in the UK" , "Punitive order" , "Order given to anti-social yobs" , "troublemaker's punishment" .)