Spreading dirt around hospital is what 2 need to become 12 (5)
I believe the answer is:
third
'what 2 need to become 12' is the definition.
I can't tell whether this definition defines the answer.
'spreading dirt around hospital' is the wordplay.
'spreading' indicates an anagram.
'around' indicates putting letters inside.
'hospital' becomes 'h'.
'dirt' is an anagram of 'tird'.
'tird' placed around 'h' is 'THIRD'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for third that I've seen before include "One of three equal parts" , "Ordinal number" , "Bronze medal position" , "Less than half, rather" , "Musical interval" .)