Press even has PM's home number (7)
I believe the answer is:
flatten
'press' is the definition.
(thesaurus)
'even has pm's home number' is the wordplay.
'even' becomes 'flat' (similar in meaning).
'has pm's home' becomes 'te' (I can't explain this - if you can you should believe this answer much more).
'number' becomes 'n'.
'flat'+'te'+'n'='FLATTEN'
Can you help me to learn more?
(Other definitions for flatten that I've seen before include "Squash" , "Make smooth or level" , "Floor" , "Raze to the ground" , "'Crush, trample (7)'" .)