‘Singlish’ as a method does not require the teacher to be a singer or player. It is easier, of course, however a recording can be used and with repeats works well. This method can be used when the singer is either unavailable or absent for a time.
There are disadvantages, however. If a song is sung live the sections can be shorter and easily repeated. If it is on tape particularly repetition is very difficult and disrupts the learning process.
With a tape it is better to play the whole song all the way through but ask them to concentrate on one line first time through, another second time through and so on.
Sometimes there are words which even a native speaker cannot interpret correctly. In this case there is no problem in discussing alternatives by using the context of the word in the song. If in doubt, go to the internet where most of the words will be found (but be careful as there will be several versions and there will often be errors or words which have been interpreted wrongly in the first place). Always look at several versions of the song and select the most suitable for your purpose.