Can a maintenance organisation with rating A perform component maintenance on the aircraft, not covered by this component maintenance by the AMM and yes by the CMM?

Oh, yeah, yeah. In relation to maintenance of aircraft components by an organisation with rating A, maintenance not covered by the AMM and yes by the CMM, Regulation 1321/2014 makes two references: 

1.- Appendix IV to Part M, paragraph 4
It argues that an A-rating organisation can maintain components in the aircraft according to the CMM. 
Limitation: That component must be fixed on the aeroplane and may only be disassembled to improve access to that component during maintenance. Such disassembly cannot generate additional maintenance. This maintenance should be included in section 1.9.1 of the Organisation’s Manual (MOE/MOM) and approved by EASA. 

2.- M.A.502 (b) 
It argues that for this maintenance it is not necessary to issue an EASA Form 1, it is sufficient to refer this maintenance in the CRS (CMM task) of the aircraft.